astro/examples/starter/public/style/global.css

* {
  box-sizing: border-box;
  margin: 0;
}

:root {
  font-family: -apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji;
  font-size: 1rem;
  --user-font-scale: 1rem - 16px;
  font-size: clamp(0.875rem, 0.4626rem + 1.0309vw + var(--user-font-scale), 1.125rem);
}

body {
  padding: 4rem 2rem;
  width: 100%;
  min-height: 100vh;
  display: grid;
  justify-content: center;
  background: #f9fafb;
  color: #111827;
}

@media (prefers-color-scheme: dark) {
  body {
    background: #111827;
    color: #fff;
  }
}